A non-fan eyewitness account of the scene:
Do you know why the armed police officer hit her? (verbatim)
Armed police officer: Excuse me, miss, please show your pass.
Ms Tang turned her head and gave him a sidelong glance, then ignored him.
The armed police officer went up to her: Excuse me, without a pass you cannot enter. Please show your pass.
Ms Tang: Get out of my way, you lot are just guard dogs. I'm in a terrible rush. Do you think you'll be able to take responsibility for my lost time?
Armed police officer: Please show some respect. No matter how urgent your business is, without a pass we will not let you in. (Stepped forward and grabbed her)
Ms Tang: Take your dog-paws off me. (Kicked him)
The armed police officer could no longer tolerate the insult, grabbed her shoulder and shoved her. This shove was angled down at 45 degrees. Armed police officers are all quite strong, so she was pushed to the ground and her face collided with the floor.
(More pictures)